Heat sinks for use in air-cooled electronic components must meet several requirements: they must maximize their surface area for maximum heat absorbtion and dissipative qualities; they must be compact; and they should be capable of relatively inexpensive manufacture. Ideally, they should be capable of manufacture in any configuration, in order to meet the various requirements of different electronic components with respect to size, shape and cooling capacity.
A Heat sink typically comprises either an independent unit mounted inside the case of an electronic device, or it is incorporated into a power source or other heat-generating component of an electronic device. Inexpensive heat sink devices for air-cooled electronic devices are typically fabricated from extruded aluminum and comprise one or more arrays of fins extending parallel to each other from a base. Air may be forced between the fins by means of a fan.
A more advanced type of heat sink is the pin fin type of heat sink, comprising an array of pins, usually cylindrical, extending from a base. Examples of the pin fin type heat sink are disclosed in U.S. Pat. Nos. 4,291,364 (Andros et al.), 4,546,405 (Hultmark et al.) and 4,733,483 (Jacoby et al.). An advantage of the pin fin type of heat sink is that it is multidirectional with natural convection; it functions equally well in any orientation, while the ordinary tinned heat sink is fully functional with natural convection only when the fins are oriented vertically.
A pin fin heat sink may comprise either a single casting, or the pins may be mounted to a base. A heat sink having separately mounted pins can be significantly less expensive than a cast unit. As well, the use of separate pins allows for the provision of a base fabricated of aluminum or other relatively light and inexpensive metal, and pins made of a highly conductive (but more expensive) metal such as brass or copper engaged to the base, for a device having lighter weight and greater heat conductive qualities. A further disadvantage of a cast unit resides in the difficulty and expense in fabricating heat sinks having varying sizes, shapes, and pin configurations, in order to meet the various requirements of different electronic devices, since each change requires the fabrication of a new mould. As well, cast metal is porous and its thermal qualities may differ from part to part. The use of separately attachable pins overcomes these drawbacks.
A drawback of a pin fin heat sink wherein the pins are mounted to the base, instead of a unit comprising a one-piece casting, is the difficulty in engaging the pins to the base in such a manner that the assembly of the device is rapid, but ensuring that intimate contact is maintained between the pins and the base, in order to maintain effective heat transfer between the base and the pins.
It is desirable as well to provide a pin fin heat sink wherein the pins are tubular rather than solid. The term "tubular" as used herein refers to any cross sectional configuration having a hollow interior. The use of a tubular pin achieves several benefits, including greater heat absorbtion and dissipation, and cost and weight savings through the reduction in material required to fabricate the device.
In order to provide a heat sink with tubular pins, the pins should capable of being readily mounted to the base in such a manner that intimate contact between the base and pin is maintained. This object has not heretofore been satisfactorily achieved.